[contact structure and manufacturing method thereof]

ABSTRACT

A contact structure and manufacturing method thereof is provided. A substrate having a first conductive layer and a dielectric layer thereon is provided. The dielectric layer has a contact opening that exposes a portion of the first conductive layer. A conductive nano-particle layer is formed on the exposed surface of the first conductive layer. Thereafter, a second conductive layer is formed inside the contact opening to cover the conductive nanoparticle layer and form a contact structure. The conductive nanoparticle layer at the bottom of the contact prevents the second conductive layer from peeling off and costs much less to produce.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the priority benefit of Taiwanapplication serial no. 92104616, filed on Mar. 5, 2003.

BACKGROUND OF INVENTION

[0002] 1. Field of Invention

[0003] The present invention relates to a semiconductor device structureand manufacturing method thereof. More particularly, the presentinvention relates to the contact structure of a semiconductor device andmanufacturing method thereof.

[0004] 2. Description of Related Art

[0005] In the fabrication of a liquid crystal display, the conductivelayers above and below an insulating layer are electrically connectedthrough a contact in the insulating layer fabricated by performing aphotolithographic and an etching process. For example, the pixelelectrode and the drain terminal of a thin film transistor in a pixelstructure are electrically connected together by performing aphotolithographic and etching process to form a contact opening in thedielectric layer that exposes the underlying drain terminal. Thereafter,the pixel electrode is deposited over the dielectric layer andelectrically connects to the drain terminal through the contact opening.

[0006] In the process of fabricating the thin film transistor, the firstmetallic layer (comprising circuit elements such as the gates and thescanning lines) and the second metallic layer (comprising the circuitelements such as the source/drain terminals and the data lines) arefabricated using aluminum or aluminum alloy. Aluminum is often selectedbecause it has the preferred conductive properties. On the other hand,the pixel electrode is fabricated using indium-tin oxide. Aside fromhaving an electrical connection with the drain terminal through acontact, the pixel electrode also connects electrically with the upperelectrode of a pixel storage capacitor. However, if the first metalliclayer and the second metallic layer are made from aluminum, theindium-tin film over the aluminum layer may initiate a galvanic reactionunder the influence of a chemical developer. As a result, the indium-tinoxide film may gradually peel off from the first metallic layer or thesecond metallic layer.

[0007] To prevent the indium-tin oxide film from peeling off the firstor the second metallic layer, a molybdenum or titanium layer is formedover the exposed first or second metallic layer within the contactopening to serve as a buffer layer. In other words, current flows fromthe indium-tin oxide electrode to the first or the second metallic layervia the molybdenum or titanium layer. Although the method is effectivein stopping the indium-tin oxide film from peeling, molybdenum ortitanium is expensive metal to work with. Moreover, sputteringmolybdenum or titanium material over a contact opening to form therequired buffer layer is a rather inefficient process. Hence, theconventional method often leads to a waste of material and an increasein production cost.

SUMMARY OF INVENTION

[0008] Accordingly, one object of the present invention is to provide acontact structure and manufacturing method thereof capable of preventingan indium-tin oxide film peeling off from an underlying metallic layerwithin a contact due to a galvanic reaction.

[0009] A second object of this invention is to provide a contactstructure and manufacturing method thereof capable of bringing down thecost of producing a conventional set up for preventing the peeling of anindium-tin oxide film from an underlying metallic layer within acontact.

[0010] To achieve these and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, theinvention provides a method of manufacturing a contact. First asubstrate having a first conductive layer and a dielectric layer thereonis provided. The dielectric layer has a contact opening that exposes thefirst conductive layer. Thereafter, a conductive nanoparticle layer isformed over the exposed first conductive layer. The conductivenano-particle layer is a metallic nano-particle layer or a siliconnano-particle layer, for example. A low temperature annealing operationis performed to consolidate the conductive nano-particle layer into anano-particle film such as a metallic nano-particle film or a metalsilicide film. Next, a second conductive layer is formed inside thecontact opening covering the nano-particle film to form a contactstructure.

[0011] In one embodiment of this invention, the conductive nano-particlelayer is formed in a charge adsorption method. First, a substrate with acontact opening thereon is immersed in a pool of special solution. Thesolution comprises a solvent and conductive nano-particles dispersethroughout the solvent. Thereafter, a positive direct current or anegative direct current is passed into the solution so that theconductive nano-particles are adsorbed towards the surface of theexposed first conductive layer to form the conductive nano-particlelayer.

[0012] In another embodiment of this invention, the conductivenano-particle layer is formed in a charge deposition method. First, apatterned photoresist layer is formed over the dielectric layer on asubstrate to expose the contact opening. The entire structure is nextimmersed in an electroplating solution. The electroplating solutioncomprises a solvent and conductive nano-particles are dispersedthroughout the solvent. Thereafter, using the substrate as an anode anda metallic electrode (for example, a platinum electrode) as a cathode,an electroplating process is carried out so that the conductivenano-particles are adsorbed towards the surface of the first conductivelayer to form a conductive nano-particle layer.

[0013] In yet another embodiment of this invention, the conductivenano-particle layer is formed in a self-assembly method. First, asubstrate with a contact opening thereon is immersed in a solutioncontaining self-assembling molecules (for example, a molecule having adisulfhydryl functional group) so that the self-assembling molecules areadsorbed towards the surface of the exposed first conductive layer.Thereafter, the substrate structure is transferred to another solutionthat comprises a solvent and conductive nano-particles dispersedthroughout the solvent. The self-assembling molecules on the firstconductive layer adsorb and accumulate conductive nanoparticles to forma conductive nano-particle layer.

[0014] This invention also provides a semiconductor device structurecomprising a conductive layer, a dielectric layer, a contact and aconductive nano-particle layer. The conductive layer is formed on asubstrate and the dielectric layer is formed on the conductive layer.The contact is formed in the dielectric layer and electrically connectedto the conductive layer. The conductive nano-particle layer is formedbetween the conductive layer and the contact. Hence, the conductivelayer is electrically connected to the contact through the conductivenano-particle layer. In this invention, the conductive nano-particlelayer is preferably a low-temperature-annealed consolidatednano-particle film.

[0015] In this invention, the conductive nano-particle layer at thebottom section of the contact opening has special cohesive propertiesthat prevent a subsequently formed conductive layer in the contactopening from peeling away.

[0016] In this invention, the conductive nano-particle layer is formedusing the charge adsorption, the charge deposition or the self-assemblymethod. The conductive nanoparticle layer serves as a buffer layersimilar to the sputtered molybdenum layer or titanium layer in aconventional method. However, the nano-particle layer is less expensiveto manufacture.

[0017] Furthermore, the conductive nano-particle layer is annealed at alow temperature to form the conductive nanoparticle film. Hence, themethod of this invention has the added advantage of bringing down theoverall thermal budget of the device.

[0018] It is to be understood that both the foregoing generaldescription and the following detailed description are exemplary, andare intended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF DRAWINGS

[0019] The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

[0020]FIGS. 1A to 1D are schematic cross-sectional views showing thesteps for fabricating a contact according to a first preferredembodiment of this invention.

[0021]FIGS. 2A to 2D are schematic cross-sectional views showing thesteps for fabricating a contact according to a second preferredembodiment of this invention.

[0022]FIGS. 3A to 3D are schematic cross-sectional views showing thesteps for fabricating a contact according to a third preferredembodiment of this invention.

DETAILED DESCRIPTION

[0023] Reference will now be made in detail to the present preferredembodiments of the invention, examples of which are illustrated in theaccompanying drawings. Wherever possible, the same reference numbers areused in the drawings and the description to refer to the same or likeparts.

[0024] In this invention, a conductive nano-particle layer is formed atthe bottom of a contact between an indium-tin oxide film and anunderlying metallic layer within the contact opening to prevent theindium-tin oxide film from peeling off due to a galvanic reaction. Inthe following, a few preferred embodiments are presented to show thesteps for producing the conductive nano-particle layer and the contact.

[0025]FIGS. 1A to 1D are schematic cross-sectional views showing thesteps for fabricating a contact according to a first preferredembodiment of this invention. As shown in FIG. 1A, a substrate 100having a conductive layer 102 and a dielectric layer 104 thereon isprovided. The dielectric layer 104 has a contact opening 106 thatexposes the conductive layer 102. If this invention is applied tofabricate the thin film transistors with a liquid crystal display, thesubstrate 100 is a glass substrate. The conductive layer 102 is thefirst metallic layer (comprising patterned gates, scan lines, commonlines and distributing terminals) or the second metallic layer(comprising patterned source/drain terminals, data lines, and the upperelectrode of pixel storage capacitor). The dielectric layer 104 is thegate dielectric layer, the passivation layer or the composite layer ofthe gate dielectric layer and the passivation layer. The contact opening106 is the contact opening for connecting the pixel electrode with thedrain terminal of a transistor or the contact opening for connecting thepixel electrode with the upper electrode of the pixel storage capacitor.

[0026] A charge adsorption method is used to form a conductivenano-particle layer at the bottom of the contact opening 106. As shownin FIG. 1B, the substrate structure 100 is immersed in a solution. Thesolution comprises a solvent and conductive nano-particles 108 dispersedthroughout the solvent. The solvent can be water, polarized organicsolvent or non-polarized organic solvent, for example. The conductivenano-particles 108 are metallic nanoparticles or silicon nano-particles,for example. The metallic nano-particles 108 are particles fabricatedusing a metallic material including, for example, gold, silver, copper,titanium or molybdenum. Each conductive nanoparticle has a size smallerthan 100 nm, for example. Furthermore, to facilitate the spreading ofthe conductive nano-particles 108 within the solvent, some surfactantmay be added to the solution. Suitable surfactant includes an organiccompound with a long carbon backbone (C>5) or an organic compound with ahydrophilic end and a hydrophobic end (for example, C₁₆H₃₅COOH).

[0027] As shown in FIG. 1C, the surface of the conductive nanoparticles108 is electrically charged. When a positive direct current or anegative direct current (for example, a voltage between 20V to 20V) isapplied to the conductive layer 102, the conductive nano-particles 108will be physically adsorbed to the surface of the exposed conductivelayer 102 and form a conductive nano-particle layer 110.

[0028] As shown in FIG. 1D, the conductive nano-particle layer 110 isannealed to consolidate the nano-particles into a nano-particle film 110a. The annealing operation is carried out at a temperature between 50°C. to 300° C. Thereafter, another conductive layer 112 is formed insidethe contact opening 106 to form a contact 114. The conductive layer 112is electrically connected to the conductive layer 102 through thenano-particle film 110a. If this invention is applied to fabricate thethin film transistors inside a liquid crystal display, the conductivelayer 112 is a transparent indium-tin oxide electrode.

[0029] In a second embodiment of this invention, a charge depositionmethod is used to fabricate the nano-particle film.

[0030]FIGS. 2A to 2D are schematic cross-sectional views showing thesteps for fabricating a contact according to a second preferredembodiment of this invention. As shown in FIG. 2A, a substrate 100having a conductive layer 102 and a dielectric layer 104 thereon isprovided. The dielectric layer 104 has a contact opening 106 thatexposes the conductive layer 102.

[0031] As shown in FIG. 2B, the substrate structure 100 is immersed inan electroplating solution. The electroplating solution comprises asolvent and conductive nanoparticles 202 dispersed throughout thesolvent. The solvent can be water, polarized organic solvent ornonpolarized organic solvent, for example. The conductive nano-particles202 are metallic nano-particles fabricated using a metallic materialincluding, for example, gold, silver, copper, titanium or molybdenum.Each conductive nano-particle 202 has a size smaller than 100 nm, forexample. Furthermore, to facilitate the spreading of the conductivenano-particles 202 within the solvent, some surfactant may be added tothe solution. Suitable surfactant includes an organic compound with along carbon backbone (C>5) or an organic compound with a hydrophilic endand a hydrophobic end (for example, C₁₆H₃₅COOH).

[0032] As shown in FIG. 2C, using the substrate 100 as an anode and ametallic electrode 201 (such as a platinum electrode) as a cathode, anelectroplating process is carried out. In the electroplating process,the conductive nanoparticles 202 are physically adsorbed to the surfaceof the conductive layer 102 to form a conductive non-particle layer 204.

[0033] As shown in FIG. 2D, the conductive nano-particle layer 204 isannealed to consolidate the nano-particles into a nano-particle film 204a. The annealing operation is carried out at a temperature between 50°C. to 300° C. Thereafter, another conductive layer 112 is formed insidethe contact opening 106 to form a contact 114. The conductive layer 112is electrically connected to the conductive layer 102 through thenano-particle film 204 a.

[0034] In yet another embodiment of this invention, the nanoparticlefilm is formed in a self-assembly process. FIGS. 3A to 3D are schematiccross-sectional views showing the steps for fabricating a contactaccording to a third preferred embodiment of this invention. As shown inFIG. 3A, a substrate 100 having a conductive layer 102 and a dielectriclayer 104 thereon is provided. The dielectric layer 104 has a contactopening 106 that exposes the conductive layer 102. The substratestructure 100 is immersed in a solution containing self-assemblymolecules 300. The self-assembly molecules 300 are, for example,molecules having a disulfhydrl functional group.

[0035] As shown in FIG. 3B, the self-assembly molecules 300 are adsorbedto the surface of the conductive layer 102. If the self-assemblymolecules 300 have a disulfhydrl function group, the molecules 300 willdehydrate on the surface of the conductive layer 102 and then chemicallybond with the conductive layer 102 to form a sulfhydrl radical surface302.

[0036] As shown in FIG. 3C, the substrate structure 100 is immersed inanother solution. The solution comprises a solvent and conductivenano-particles 304 dispersed throughout the solvent. The solvent can bewater, polarized organic solvent or non-polarized organic solvent, forexample. The conductive nano-particles 304 are metallic nano-particlesor silicon nano-particles. The metallic nano-particles are fabricatedusing a metallic material including, for example, gold, silver, copper,titanium or molybdenum. Each conductive nano-particle 304 has a sizesmaller than 100 nm, for example. Furthermore, to facilitate thespreading of the conductive nano-particles 304 within the solvent, somesurfactant may be added to the solution. Suitable surfactant includes anorganic compound with a long carbon backbone (C>5) or an organiccompound with a hydrophilic end and a hydrophobic end (for example,C₁₆H₃₅COOH). The conductive nanoparticles 304 in the solution areadsorbed by the sulfhydrl radical 302 on the conductive layer 102 toform a conductive nano-particles layer 304 a.

[0037] As shown in FIG. 3D, the conductive nano-particle layer 304 a isannealed to consolidate the nano-particles into a nano-particle film 304b. The annealing operation is carried out at a temperature between 50°C. to 300° C. Thereafter, another conductive layer 112 is formed insidethe contact opening 106 to form a contact 114. The conductive layer 112is electrically connected to the conductive layer 102 through thenano-particle film 304 b.

[0038] In this invention, the conductive nano-particle films 110 a, 204a and 304 b at the bottom of the contact opening 106 are formed usingthe charge adsorption, the charge deposition or the self-assemblymethod. The nano-particle film between the indium-tin oxide film 112 andthe underlying conductive layer 102 within the contact opening 106prevents the indium-tin oxide film 112 from peeling away from theconductive layer 102 due to a galvanic reaction.

[0039] This invention also provides a semiconductor device structurecomprising a conductive layer 102, a dielectric layer 104, a contact 108and a conductive nano-particle layer 110 or 204 or 304 a. The conductivelayer 102 is formed over the substrate 100 and the dielectric layer isformed over the conductive layer 102. The contact 108 is formed in thedielectric layer 104. Furthermore, the contact 108 and the conductivelayer 102 are electrically connected together. The conductivenano-particle layer 110 or 204 or 304 a is formed between the conductivelayer 102 and the contact 108. The conductive nano-particle layer 110 or204 or 304 a is a metallic nano-particle layer or a siliconnano-particle layer. Preferably, the nanoparticles in the conductivenano-particle layer 110 or 204 or 304 a are further consolidated to forma nano-particle film 110 a or 204 a or 304 b, for example, a metallicnanoparticle film or a silicon nano-particle film.

[0040] In summary, major advantages of this invention include: 1. Theconductive nano-particle layer formed at the bottom of a contact openingis able to prevent a subsequently formed conductive layer inside thecontact opening from peeling off due to a galvanic reaction. 2. Theconductive nano-particle layer is formed using the charge adsorption,the charge deposition or the self-assembly method. The conductivenano-particle layer serves as a buffer layer similar to the sputteredmolybdenum layer or titanium layer in a conventional method. However,the nano-particle layer is less expensive to manufacture. 3. Theconductive nano-particle layer is annealed at a low temperature to formthe conductive nano-particle film. Hence, overall thermal budget of thedevice is reduced.

[0041] It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of the presentinvention without departing from the scope or spirit of the invention.In view of the foregoing, it is intended that the present inventioncover modifications and variations of this invention provided they fallwithin the scope of the following claims and their equivalents.

1. A method of manufacturing a contact, comprising the steps of:providing a substrate having a first conductive layer and a dielectriclayer thereon, wherein the dielectric layer has a contact opening thatexposes a portion of the first conductive layer; forming a conductivenano-particle layer on the exposed surface of the first conductivelayer; and forming a second conductive layer inside the contact openingto cover the conductive nano-particle layer.
 2. The method of claim 1,wherein the conductive nanoparticle layer comprises a metallicnano-particle layer.
 3. The method of claim 1, wherein the conductivenanoparticle layer comprises a silicon nano-particle layer.
 4. Themethod of claim 1, wherein the nano-particles inside the conductivenano-particle layer has an average size smaller than 100 nanometers. 5.The method of claim 1, wherein after the step of forming the conductivenano-particle layer, furthermore comprises performing an annealingprocess.
 6. The method of claim 5, wherein the annealing process isperformed at a temperature between about 50° C. to 300° C.
 7. The methodof claim 1, wherein the step of forming the nano-particle layer includesperforming a charge adsorption process, comprising the steps of:immersing the substrate with the contact opening already formed thereonin a solution, wherein the solution contains dispersed conductivenano-particles; and passing a direct current into the solution so thatthe conductive nano-particles are adsorbed and adhered to the surface ofthe first conductive layer.
 8. The method of claim 7, wherein thesolution furthermore comprises some surfactant.
 9. The method of claim1, wherein the step of forming the nano-particle layer includesperforming a charge deposition process, comprising the steps of: forminga patterned photoresist layer over the dielectric layer that exposes thecontact opening; immersing the substrate structure into anelectroplating solution, wherein the electroplating solution containsdispersed conductive nano-particles; and performing an electroplatingprocess using the substrate as an anode and a metallic electrode as acathode to form the conductive nano-particle layer on the surface of thefirst conductive layer.
 10. The method of claim 9, wherein theelectroplating solution furthermore comprises some surfactant.
 11. Themethod of claim 1, wherein the step of forming the nano-particle layerincludes performing a molecular self-assembly process, comprising thesteps of: immersing the substrate with a contact opening already formedthereon in a solution having self-assembly molecules so that theself-assembly molecules are adsorbed to the surface of the firstconductive layer; and immersing the substrate in another solution,wherein the solution contains dispersed conductive nano-particles sothat the nano-particles are adsorbed towards the layer of self-assemblymolecules on the first conductive layer to form the conductivenano-particle layer.
 12. The method of claim 11, wherein the solutionfurthermore comprises some surfactant.
 13. A semiconductor devicestructure, comprising: a conductive layer formed on a substrate; adielectric layer formed on the conductive layer; a contact formed in thedielectric layer, wherein the contact and the conductive layer areelectrically connected; and a conductive nano-particle layer formedbetween the conductive layer and the contact.
 14. The semiconductordevice structure of claim 13, wherein the conductive nano-particle layercomprises a metallic nano-particle layer.
 15. The semiconductor devicestructure of claim 13, wherein the conductive nano-particle layercomprises a silicon nano-particle layer.
 16. The semiconductor devicestructure of claim 13, wherein conductive nano-particles in theconductive nano-particle layer have an average size smaller than 100nanometers.
 17. The semiconductor device structure of claim 13, whereinthe conductive nano-particle layer comprises a nano-particleconsolidated nano-particle film.
 18. The semiconductor device structureof claim 13, wherein material forming the conductive layer comprisesaluminum.